Novel Compound Semiconductor Nanowires
Materials, Devices, and Applications
edited by
Fumitaro Ishikawa
Irina A. Buyanova
Published by
Pan Stanford Publishing Pte. Ltd.
Penthouse Level, Suntec Tower 3
8 Temasek Boulevard
Singapore 038988
Email: editorial@panstanford.com
Web: www.panstanford.com
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Novel Compound Semiconductor Nanowires: Materials, Devices, and Applications
Copyright © 2018 Pan Stanford Publishing Pte. Ltd.
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ISBN 978-981-4745-76-5 (Hardcover)
ISBN 978-1-315-36440-7 (eBook)
Printed in the USA
Hiroyuki
and Irina A. Buyanova
2.2.1 First Self-Organization of GaN Nanocolumns 33
2.2.2 Growth of GaN Nanocolumns on (0001) Sapphire Substrates with AlN Buf fer Layers 37
2.2.3 AlN-BL Effect on Crystal Quality of Self-Assembled GaN Nanocolumns on (111) Si Substrates 39
2.3 Self-Organized Nanocolumn LEDs 42
2.3.1 PL Emission Characteristics of InGaN Quantum-Disk Nanocolumns 42
2.3.2 Champagne-Glass InGaN-Based Nanocolumn LEDs 45
2.3.3 Micro-EL Property of InGaN/GaN Champagne-Glass Nanocolumn LEDs 47
2.3.4 Micro-PL Measurement of a Single InGaN-SQD Nanocolumn and Strain Relaxation Ef fect in Nanocolumns 50
2.3.5 Flip-Chip InGaN/GaN Nanocolumn LED with One-Micron-Diameter Injection Area 51
2.3.6 Ultraviolet Nanocolumn LEDs on Si Using Underlying GaN Nanocolumn Template 55
2.3.7 Self-Organization of GaN Nanocolumns on Graphene/SiO2/Si 57
2.3.8 Effect of Be-Doping on InGaN/GaN Nanocolumn LED Structure 60
2.4 Dislocation Suppression Ef fects of Nanocolumns 62
2.4.1 Dislocation Filtering Ef fect of GaN Nanocolumns as a Function of Nanocolumn Diameter 62
2.4.2 Critical Thickness of InGaN/GaN Nanocolumns as a Function of Nanocolumn Diameter 65
2.5 Selective-Area Growth of GaN Nanocolumns 68
2.5.1 Development of SAG of GaN Nanocolumns 68
2.5.2 Selective-Area Growth of GaN Nanocolumns on Si Using Nitridated Al Metal Pattern 69
2.5.3 Ti-Mask SAG of GaN Nanocolumns on GaN Template/Sapphire Substrates 72
2.6 Emission Color Control and Multicolor Integrated Nanocolumn LEDs 77
2.6.1 Emission Color Control of InGaN-Based Nanocolumn Arrays by the Nanocolumn Structural Parameters 77
2.6.2 Monolithic Integration of Nanocolumn LEDs with Dif ferent Emission Colors 84
2.7 LEDs Based on Uniform Nanocolumn Arrays 86
2.7.1 Green-Light Nanocolumn LEDs with Triangular-Lattice Uniform Arrays of InGaN-Based Nanocolumns 86
2.7.2 Yellow-Light Nanocolumn LEDs with High Directional Radiation Beams 90
2.8 Lasing Emission Based on Nanocolumn Photonic Crystal Effect 93
2.9 Summary and Future Prospects 94
Part II: Materials
3. Novel GaNP Nanowires for Advanced Optoelectronics and Photonics
Irina A. Buyanova, Charles W. Tu, and Weimin M. Chen
3.1 Introduction
3.2 Optimizing Light Emission Ef ficiency of GaNP Coaxial Nanowires
3.2.1 Sample Structure
3.2.2 Defect Identification
3.2.3 Impacts of Defects on Carrier Recombination
3.2.4 Optimized Design
3.3 Effects of Polytypism on Optical Properties and Band Structure
3.3.1 Effects of Polytypism on Radiative Recombination
3.4
3.5
3.3.2 Ef fects of Nitrogen Content on Optical Properties of Zinc Blende and Wurtzite
Emitters from GaNP Nanowires
4. GaNAs-Based Nanowires for Near-Infrared
Irina A. Buyanova, Fumitaro Ishikawa, and Weimin M. Chen
4.1
5.
4.3 Eff
4.3.1
4.4
Wojciech M. Linhart, Szymon J. Zelewski, Fumitaro Ishikawa, Satoshi Shimomura, and Robert Kudrawiec
5.1
5.2
5.3
5.4
5.5 Photoacoustic Spectroscopy of GaAsBi Nanowires
5.6 Summary
6. Ferromagnet ic MnAs/III–V Hybrid Nanowires for Spintronics
Shinjiro Hara
6.1 Introduction
6.2 Experimental
6.2.1 Selective-Area Growth of Semiconducting Nanowire Templates
6.2.2 Endotaxy of Ferromagnetic MnAs Nanoclusters
6.2.3
6.3
6.3.1
6.3.1.1
6.3.2
6.3.2.1 Endotaxial formation of MnAs/InAs heterojunction NWs
6.3.2.2 Magnetic characterization of MnAs/InAs heterojunction NWs
6.3.2.3 Endotaxial growth mechanism of MnAs NCs in InAs NWs
6.4
7. GaAs-Fe3Si Semiconductor–Ferromagnet Core–Shell Nanowires for Spintronics 221
Maria Hilse, Bernd Jenichen, and Jens Herfort
7.1 Introduction
7.2 Epitaxial Growth
7.3 Morphology
8.
7.4
Fumitaro Ishikawa and Naoki Yamamoto
8.1
8.2
8.2.1
8.2.2
9.3.2 The Impact on the Structure of AlGaAs
9.4 GAAs (Core)/SrTiO3 (Shell) NWs
9.4.1 The Growth of GaAs/SrTiO3 NWs 302
9.4.2 Structure, Morphology, and Chemistry at the GaAs/SrTiO3 Interface 305
Part III: Devices and Applications
10. Ga(In)N Nanowires Grown by Molecular Beam Epitaxy: From Quantum Light Emit ters to Nanotransistors 319
Žarko Gačević and Enrique Calleja
Bot tom-Up versus Top-Down Approach
SAG Homoepitaxy: NWs Growth Mechanisms
10.2.3 Discussion: SA Heteroepitaxy versus SAG Homoepitaxy
10.3 Ordered InGaN/GaN NWs as Arrays of Quantum Light Emitters
10.3.1 III-Nitride Quantum Dots as Single Photon Sources
10.3.2 III-Nitride Dot-in-a-Wire SPSs: Top-Down versus Bottom-Up Approach 337 10.3.3 InGaN/GaN NW SPS Grown by SAG MBE 339 10.3.4 Discussion
10.4 GaN Nanowire Fabrication
10.4.1 GaN NWs as Field-Ef fect Nanotransistors
10.4.2 Fabrication and Processing Approaches: Bot tom-Up versus Top-Down 348
10.4.3 A Semi-Cylindrical Top-Gate GaN NW MESFET
12. InP/InAs Quantum Heterostructure Nanowires 39
Guoqiang Zhang, Kouta Tateno, and Hideki Gotoh
12.5.1
Wei Guo, Pallab Bhattacharya, and Junseok Heo
13.3
13.5
13.5.1
Katsuhiro Tomioka, Junichi Motohisa, and Takashi Fukui
Foreword
As a researcher working on semiconductor nanostructures for about 50 years, it is my great pleasure to write a foreword for this book, which has been edited by Drs F. Ishikawa and I. Buyanova to cover recent research accomplishments on the epitaxial growth, physics, and device applications of semiconductor nanowire structures.
As is well known, most of key semiconductor devices, such as field-effect transistors (FETs) and laser diodes (LDs) make use of very thin layers as their core parts, since the control of channel conductance in FETs by gate voltage and that of optical gains in LDs by injected carriers can be efficiently achieved only if the channel layer of FETs and the active layer of LDs are sufficiently thin. These core layers, however, cannot be made too thin, since the quantum confinement of carriers in such layers leads to an excessive rise of the carrier energy and possibly weakens the carrier confinement.
As a result, these layers are formed with the thickness of a few to 10 nm by employing advanced epitaxy and other semiconductor techniques so that carriers are well confined and move freely only along the layer, while their motion normal to the layer is quantized. The two-dimensional (2D) nature of these carriers has induced a variety of important consequences, such as the formation of a series of 2D sub-bands with a step-like density of states, and the enhancement of excitonic effects. Consequently, various new devices, such as resonant tunneling diodes and inter-sub-band photodetectors and lasers, have been realized and new phenomena, such as quantum Hall effect, have been discovered. While the thinning of these core layers has allowed the progress of advanced devices and the exploration of new physics of 2D carriers, the width reduction of such layers or films to form wire structures, such as narrow FET channels, has been done mainly in the field of LSIs to shrink devices for higher integration and to reduce the current and power consumption. It is also noted that the use of nanowire channels reduces the short-channel effect of FETs, as the gate around the wire acts more effectively than that
Foreword
in planar FETs. Although this down-scaling has been widely done, the typical width of FETs is set still at 100 nm or above to keep enough current drive capabilities.
Possibilities of squeezing the wire width down to 10 nm to confine electrons quantum mechanically and to use such 1D electrons for possible device applications had not been discussed until 1975, when I analyzed electron transport in coupled nanowire or planar superlattice structures. In 1980, potentials of quantum nanowire FETs were studied also by me. In 1982, Arakawa and I proposed and studied the possible use of quantum wires and quantum dots as gain media of semiconductor lasers.
Although such nanowire structures could not be formed in those early years, several groups started exploratory works to develop various methods that have enabled the formation of nanowire structures. The attempts are categorized into the three groups:
(a) top-down approach, based on the lithographic film patterning and the passivation
(b) bottom-up approach, based on the wire growth on selfassembled nanoparticles
(c) hybrid approach, which combine various patterning and selective growth processes
This book covers key results on the epitaxial growth of nanowires that belong to either group (b) or group (c).
Thanks to the progress of these fabrication methods, the formation of nanowires has been greatly facilitated, though there are still a lot of problems to be taken care of. As a consequence, a large number of studies have been made to clarify the physics and chemistry of various nanowire structures and to disclose unexplored potentials of nanowire-based devices, such as nanowire LEDs and solar cells.
I wish to close this foreword by wishing that this book promotes more research activities and accelerates the progress in the field.
Hiroyuki Sakaki
Professor Emeritus, University of
Tokyo
President, Toyota Technological Institute
Nagoya, Japan September 2017
Preface
The area of nanoscale science and technology is currently gaining increasing attention because of intriguing fundamental physics at the nanoscale, as well as potential applications of the lowdimensional structures in nanoscale electronics, optics, energy storage, and biology. The fabrication of these structures from crystalline semiconductors is now possible with a high degree of complexity, due to impressive developments in epitaxial growth techniques. Molecular beam epitaxy and metalorganic vapor phase epitaxy approaches are among the representative techniques utilized for the growth of low-dimensional semiconductor heterostructures with an atomic structural accuracy and precision. High-quality, single-crystalline III-V one-dimensional (1D) nanowire heterostructures are an example, promising for the nextgeneration nanoscale photonic and electronic devices, such as highly efficient nanowire light-emitting diodes, lasers and solar cells, as well as high-speed transistors. The key advantages of employing III-V semiconductor materials (i.e., nitride-, phosphide, and arsenide-related heterostructure systems) for the realization of these devices include a high carrier mobility and superior optical properties. Furthermore, the developed epitaxial growth techniques enable electronic carrier control through the formation of quantum structures and precise doping, which can be introduced into a nanowire system. Most recently, it also became possible to fabricate III-V nanowires from highly mismatched alloys formed from III-V compounds with a large miscibility gap, or, alternatively, by the formation of hybrid heterostructures between a semiconductor and another material system based on, for instance, magnetic half metals and oxides. This book reviews the recent progress of such novel III-V semiconductor nanowires, covering a wide range of aspects from the epitaxial growth to the device applications. The prospects of such advanced 1D structures for nanoscience and nanotechnology are also discussed.
The book is organized as follows. A general overview of the area of one-dimensional structures is provided in Chapters 1 and 2. Specifically, Chapter 1 reviews the nanowire heterostructures for electrical and optical applications, focusing on the basic concepts and growth methods and the challenges of controlling the structure and the composition, and providing examples of selected nanowire devices. Chapter 2 describes the historical progress of molecular beam epitaxy of nitride nanocolumns and related nanocolumn emitters. The authors of this chapter have pioneered the growth of high-quality, metastable InGaN nanocolumns and related devices, which has opened the possibility of their applications in optical devices.
Chapters 3–9 review the properties of nanowires derived from novel strategic materials fabricated by epitaxial growth techniques.
Chapters 3–5 describe the highly mismatched dilute nitride and dilute bismide systems, which allow increased tunability in the band gap energy and lattice constants compared with conventional III-V semiconductor compounds and alloys. In Chapter 3, the structural and optical properties of GaNP nanowires are discussed along with their potential for future optoelectronic applications. In addition to significant improvements in the radiative efficiency, defect engineering via alloying with nitrogen is shown to be advantageous for the realization of polarized nano light sources and also for improving energy harvesting. In Chapter 4, structural and optical properties as well as the possible applications of GaNAs nanowires are reviewed. It is shown that alloying with nitrogen leads to the passivation of the nanowire surface and the formation of embedded quantum dot-like emitters. The existing research on dilute III-V-Bi nanowires, particularly dilute GaAsBi nanowires, is reviewed in Chapter 5. These novel alloys are of potential importance as infrared emitters with suppressed intrinsic non-radiative recombination losses at high temperature.
Chapters 6 and 7 are devoted to the characterization of nanowires based on novel spintronic materials. Chapter 6 describes experimental results from hybrid structures of ferromagnetic MnAs and non-magnetic III-V compounds and demonstrates their potential for magneto–nanoelectronic or spintronic device applications. In Chapter 7, the results from the GaAs–Fe3Si semiconductor-ferromagnetic hybrid nanowires Preface
are presented. A high Curie temperature is a prerequisite for the application of these materials in spintronic devices, and the binary Heusler alloy Fe3Si is a promising material in this sense.
Chapters 8 and 9 discuss hybrid nanowires consisting of GaAs and oxides. In Chapter 8, the synthesis of GaAs/AlGaOx nanowires combining molecular beam epitaxy and subsequent wet oxidation is presented. The characteristic broad visible light emission from the AlGaOx materials is demonstrated. Chapter 9 describes the growth and properties of GaAs/SrTiO3 core–shell nanowires providing strategies for the synthesis of these high-quality hybrid structures. It demonstrates the feasibility of monolithical integration between the monocrystalline epitaxial shell of functional oxides and the nanowire, promising for the development of heterostructures that couple light emission/absorption and piezoelectricity or ferroelectricity.
The recent progress in device applications of nanowires is reviewed in Chapters 10–14. An overview of growth and applications of GaN nanowires together with a brief history of the related discoveries is given in Chapter 10. Both top-down and bottom-up approaches for the formation of nanowire arrays are presented. Additionally, the applications of these materials as quantum light emitters and nano-transistors are discussed. In Chapter 11, the potential of InP-related light-emitting devices is reviewed based on the in-depth investigations of the nanowire growth and device fabrication. The growth and the future prospect of InP/InAs nanowires for applications in field-effect transistors are described in Chapter 12. The achieved reproducible low-temperature synthesis of radial InP/InAs structures grown with top-down patterning and the demonstrated use of these structures as field-effect transistors highlight the potential of these materials in beyond-CMOS technologies. Chapter 13 describes the growth of InGaN nanowires and their applications in green light-emitting diodes, in lasers with a photonic crystal cavity, and also in photovoltaic devices. Chapter 14, the last chapter, provides a comprehensive overview of the historical development and the state-of-the-art of semiconductor nanowire transistors and solar cells. The emphasis is on the progress of IIIV nanowires grown via metalorganic vapor phase epitaxy and their applications. This chapter also summarizes the most Preface
representative achievements in nanowire device applications for a wide range of III-V and group-IV materials and oxides.
We would like to express our gratitude to all contributors for their willingness to share with the readers their experience and in-depth insights into the exciting area of semiconductor nanowires. We hope that the comprehensive collection of the review articles on the current status of novel nanowire materials and systems provided in the book will stimulate further research efforts in this exciting field. F. I acknowledges the transfer of the experience and growth techniques at the initial stage of the nanowire study from Masahito Yamaguchi (who sadly passed away in 2013) and Yoshio Honda.
We are grateful to Stanford Chong and Arvind Kanswal of Pan Stanford Publishing for the invitation of this book editing and continuous support during the preparation.
Fumitaro Ishikawa, Matsuyama Irina A. Buyanova, Linköping September 2017 Preface
Part I Overview
Chapter 1
Introduction: Transcending
Limits of Epitaxial Thin-Film Heterostructures
Semiconductor heterostructures are the basis for modern solidstate electronic and optoelectronic devices, including field-effect transistors, lasers, and light-emitting diodes. Heterostructures enable the engineering of energy band discontinuities and builtin potentials to control charge carrier injection, confinement, transport, and recombination. Charge carrier transport may occur along heterointerfaces, as in field-effect transistors, or across heterointerfaces, as in lasers and light-emitting diodes. Heterostructures can be formed by heteroepitaxy, a process in which a one crystalline material is grown on another crystalline material with a well-defined orientation between the two crystals. Beyond forming active junctions, thin film heteroepitaxy is also used to create large area substrates of high quality when bulk crystals are either unavailable or prohibitively expensive. For example, a rather small number of crystalline semiconductor substrates (e.g., Si, GaAs, sapphire) are of sufficiently high quality and low cost to support large-scale device fabrication, and they are available with limited crystal orientations. Substrates of semiconductor alloys and/or unusual crystal orientations are generally grown as thin films on commercially available substrates, provided the substrates are compatible in terms of thermodynamic stability, crystal structures, and lattice constants. When appropriate combinations are identified, heteroepitaxy can also be exploited for device integration. Practical operation of many electronic and optoelectronic devices often requires integration of multiple components of different functions. Heteroepitaxy can provide an approach by which the multiple components are combined economically.
Key challenges in heteroepitaxial film growth include the control of growth morphology, stress, strain, defects, and polarity. When mismatches of lattice constants and/or thermal expansion coefficients between the thin film and substrate are substantial, dislocations form to relax strain at the heterointerfaces. In general, structural defects, including dislocations, antiphase domains or boundaries, point defects, and precipitates are detrimental to the performance and reliability of devices by
Introduction
forming midgap states that act as charge carrier traps and scattering/recombination centers. The mitigation of defect formation and the reduction of defect density are key goals of heteroepitaxy, particularly in forming the active region of devices. Approaches to suppress formation of defects include nanopatterning, compositional grading, and buffer layer growth [1–3]. However, these methods may provide incomplete suppression of dislocation formation or involve complicated processing. Epitaxial nanowire heterostructures enable crystal growers to transcend some limitations of conventional thin-film heterostructures to open up new opportunities in device engineering. This chapter provides a brief introduction to the opportunities and challenges created by nanowire heterostructures, including the basic structures and concepts. In addition, we provide some perspective on structure–property relationships using select examples taken primarily from the literature on group III-V nanowires. Epitaxial heterostructure nanowires [4] combine two or more segments of different composition and/or doping while maintaining epitaxial relationships between the segments [4, 5]. In contrast to the conventional planar heterostructures, epitaxial heterostructure nanowires can accommodate significant interfacial strain at nanowire–substrate interfaces and heterojunction interfaces without defect formation due to their small lateral dimensions. The minimization of defect induced scattering and recombination improves the control of injection, separation, and collection of charge carriers, enhancing device performance. Moreover, the efficient strain accommodation in epitaxial heterostructure nanowires widens the range of materials that can be combined into heterostructures, including the range of substrates on which nanowires can grow. By enabling a wider range of material combinations, nanowires provide greater flexibility in selecting bandgaps and band offsets. The monolithic growth of III-V nanowires on Si substrates in particular provides the opportunity to integrate optoelectronic devices with Si-based complementary metal-oxide semiconductor (CMOS) technology [6]. Additionally, epitaxial nanowire growth methods can be used to create combined radial/axial heterostructures and mixed dimensional heterostructures such as dot-in-a-nanowire, which can provide new or improved functionality.
This chapter is not a comprehensive review of epitaxial nanowire heterostructures. Rather, it provides a perspective on structure–property relationships in epitaxial nanowire heterostructures by illustrating basic concepts with selected examples, primarily from III-V materials. Accordingly, Section 1.2 introduces basic concepts in the growth and structure of epitaxial heterostructure nanowires. Section 1.3 outlines goals for controlling structure and composition. Section 1.4 describes relationships between structures and properties and provides select recent examples of nanowire devices with an emphasis on electrical and optical devices.
1.2 Target Heterostructures and Growth Methods
Heterostructures may be formed within nanowires or between a nanowire and a growth substrate. We first consider the epitaxial growth of nanowires on a substrate. In homoepitaxy, nanowires are grown on a substrate of the same composition and phase. The crystal structure, lattice constants, and orientation are maintained across the nanowire substrate boundary without the formation of strain fields at the interface. In heteroepitaxy, nanowires are grown on a substrate of different material, typically with some degree of lattice mismatch. The finite and small cross section of nanowires implies that the total interfacial strain energy can be simply controlled with nanowire diameter. Therefore, the total interfacial strain energy can be held below the threshold for nucleation of a dislocation. Furthermore, any dislocations that cannot propagate parallel to the growth direction eventually terminate. In van der Waals epitaxy [7], nanowires are grown on a substrate that does not form covalent bonds with the nanowire. Interactions are sufficiently weak to prevent dislocation formation, but strong enough to provide some degree of orientation. Epitaxial heterostructures can also be formed within individual nanowires as axial heterostructures, radial heterostructures, and combinations thereof. In axial heterostructures, heterointerfaces are perpendicular to the
Target Heterostructures and Growth Methods
nanowire growth axis. When the material is deposited epitaxially on the surface of a nanowire, a radial heterostructure is formed. Complex heterostructures combining both radial and axial heterostructures can be fabricated by modifying growth conditions to favor one growth mode or the other.
Nanowires are the result of highly anisotropic crystal growth driven by preferential nucleation on a single facet or set of facets. There are many ways to achieve preferential nucleation, but the vapor–liquid–solid (VLS) growth mechanism is perhaps the most often used. Precursor molecules in the vapor phase are chemisorbed and dissociated at the surface of a liquid alloy droplet, and crystal growth occurs at the solid–liquid interface with the crystal diameter defined by the size of the droplet. Metals that alloy with semiconductors to form deep eutectics, such as Au, are used to seed VLS growth. However, the incorporation of metal impurities into the growing nanowires is a concern for many applications. For example, Au impurities in Si nanowires form mid-gap impurity levels and act as charge carrier traps and recombination centers [8]. VLS growth also encompasses “self-catalyzed” processes, such as the growth of GaAs nanowires from a Ga droplet, which avoid the use of an impurity species. Furthermore, nanowires can be grown in the absence of seed particles if growth on a particular facet is strongly preferred. In all cases, the locations at which nanowires grow can be influenced by patterning. For growths without a seed particle, the growth location can be controlled by selective area epitaxy, which involves creating openings in a substrate masked by a barrier layer. Nanowires grow epitaxially from the openings, while the barrier layer promotes precursor diffusion and inhibits nucleation. Selective area epitaxy is typically implemented using metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). In MOCVD, metalorganic precursors are preferentially decomposed on the open surface with respect to mask, and undecomposed precursors diffuse to the open areas. In MBE, molecules and atoms have higher sticking coefficients on the open surface compared to the mask layers, and adatoms impinging on the masked area diffuse to the mask opening.
1.3 Controlling Structure and Composition: Achievements and Challenges
The major goals of nanowire heterostructure growth are to control position, orientation, and crystallinity. The position is typically controlled by patterning the growth substrate, as mentioned above. The orientation is established by some form of epitaxy, including standard epitaxy, van der Waals epitaxy, and graphoepitaxy. Finally, most nanowire growth processes produce crystalline material, but the defect type and density is strongly influenced by both the substrate and growth conditions, as for thin film growth. This section briefly reviews the role of epitaxy in controlling position, orientation, and crystallinity.
1.3.1 Epitaxy on Substrates
In heteroepitaxial growth of nanowires, as with thin films, the combination of substrate and nanowire is typically chosen to avoid the formation of misfit dislocations due to lattice mismatch between the nanowires and substrate. More specifically, there is in principle a critical nanowire diameter above which plastic deformation occurs via the formation of misfit dislocations at the interface of a nanowire and a substrate for a given lattice mismatch [9, 10]. While strain is shared by a nanowire and a substrate, elastic relaxation occurs primarily along the growth axis of the nanowire [11]. Tomioka et al. reported that InAs and GaAs nanowires grown on Si (111) substrate have misfit dislocations at the nanowire–substrate interface with a periodicity corresponding to the values expected from lattice mismatch [12, 13].
Another important consideration for heteroepitaxial growth is the preferred growth direction, which is influenced by the substrate as well as the seed particle (if used) and growth conditions. For the integration of nanowire arrays into devices, the growth of nanowire arrays oriented in a common direction, usually perpendicular to the substrate, is desired. Most nanowires prefer to grow along <111> directions, which favor substrates that are lattice matched to the selected nanowire (111) planes.
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“A new kind of boys’ book and a good kind, too.”
Outlook 127:110 Ja 19 ’21 60w
“It is not difficult to imagine that fathers with boys of eighteen will find Mr Soule an altogether enjoyable companion.”
Springf’d Republican p8 Ja 4 ’21 240w
LIVERMORE, THOMAS LEONARD. Days
and events, 1860–1866. il *$6 (3c) Houghton 973.7
20–5734
This posthumous book, published by the author’s family and recording Colonel Livermore’s experiences in the Civil war, was begun immediately after the conclusion of the war, while its events were still fresh in his mind. Henry M. Rogers in his introduction gives a brief sketch of the author’s life.
“Colonel Livermore has been known for a long time by his work on ‘Numbers and losses in the Civil war, ’ which has been one of the most valuable contributions to our military history. The work now before us is of an entirely different character and reflects the ability of the author from a new and no less interesting angle.” Eben Swift
Am Hist R 25:734 Jl ’20 600w
“The volume ought to take its place as a real ‘ source book’ for commentators on the history of that conflict. There is much of entertainment in the narrative, which is frank to a degree and often vigorous, fresh, and significant in its criticisms.”
Outlook 124:431 Mr 10 ’20 100w
LIVINGSTON, ROBERT. Land of the great outof-doors. il *$1.75 (9c) Houghton
20–17525
When they are about five and six years old, Penrose and Penelope, known as Pen and Penny, are taken to the country to live on a farm. This little story tells of their daily life, beginning in the spring time and continuing to Christmas. In some of the chapters Pen tells of his doings, in others Penny gives her view of things. The colored pictures are by Maurice Day.
Ind 104:380 D 11 ’20 40w
“The impersonator frequently forgets, in his desire to have the valuable information imparted, that he is under contract to use the speech of childhood. However, the stories will undoubtedly find favor with the little folk, and their atmosphere is fresh and wholesome.” M. H. B. Mussey
Nation 111:sup672 D 8 ’20 80w
“It will prove excellent to read aloud, or to give to children who are just beginning to read for themselves.” Hildegarde Hawthorne
N Y Times p4 D 5 ’20 120w
Springf’d Republican p8 N 18 ’20 80w
LOCK, H. O.[2] Conquerors of Palestine through forty centuries. *$3 Dutton 956.9
20–4566
“The history begins with the ancient Egyptians, relates the campaigns and conquests of the Jews, the Assyrians and Babylonians, the Greeks, Romans, Arabs, the picturesque warriors of the Crusades, the French, and then the British. The intervening history is briefly sketched, to make a connected narrative. The book has an introduction by Field Marshal Viscount Allenby, commanderin-chief of the British forces in Palestine.” Springf’d Republican
“Major Lock has produced a readable sketch of a large subject. The map attached to the book is ingeniously contrived to illustrate the many periods of history on which Major Lock touches.”
Spec 122:86 Ja 17 ’20 100w
Springf’d Republican p8 N 6 ’20 60w
LOCKE, GLADYS EDSON. Ronald o ’ the moors. il *$1.75 (2½c) Four seas co.
This historical novel is staged on the Dartmoor bogs in the reign of George II. Dartmoor was a hot-bed of Jacobite sympathy, and Sir Roger Hetherington had been sent down from the court of St James to guard Penraven Castle, the center of Jacobite activity, and to capture wild Ronald o ’ the moors, a highwayman and night rider who made Hanoverians his particular prey. Sir Roger was far from welcome at Penraven Castle, indeed he soon realized that he was in the midst of bitter enemies. What made the success of his undertaking even more doubtful, however, was the fact that he at once lost his heart to Lady Edris Penraven, the mistress of the castle he was sent to spy upon, and that Ronald seemed to be as elusive as the will o ’ the wisps that flitted over the moor. Altogether Sir Roger’s plans did not work out just as he had shaped them, but the end of the story, altho it leaves him exiled in France, yet brings him happiness as well, since he shares Lady Edris’s fate.
“The book is about on a par with the average of its class, fiction of which the authors seem to be under the impression that vital interest is imparted by a liberal supply of oaths and expletives, and the use of archaic language whether appropriate to the period or otherwise.”
The hero is a man of great intellectual power, dynamic physical energy and sudden quixotic impulses. After he has spent eighteen years of voluntary exile in China self imposed because he fears to compromise the girl he loves and two years of hermitlike seclusion on the moor with a fascinating and erudite young Chinese student, a German bomb from a zeppelin shocks him into a dazed knowledge of the European war. Wide awake, action hungry, he scorns his former achievements as a mathematical genius and brilliant Chinese scholar, plunges into political activities, gets “hitched on to” the war, and becomes the man of the hour. The old distasteful personal ties are broken through his wife’s death and the lapse of the years. New ones are forged and he learns that he has a fine son of whom he had not even dreamed. Life in London has become sweet and full and he desires no change. But once more the quixotic impulse asserts itself a sacrifice becomes necessary for the sake of his officer son ’ s career, and he is off to China again.
“A typically interesting Locke story. The book ends rather weakly.”
Booklist 16:204 Mr ’20
“Mr Locke has written many stories better than ‘The house of Baltazar,’ but there are few of them in which his neglected opportunities were greater. The truth is that he, like many other novelists, is obsessed by the necessity of making the war and its farreaching effects a part of his fiction.” E. F. E.
Boston Transcript p6 Ja 21 ’20 1260w Dial 68:537 Ap ’20 20w Ind 103:54 Jl 10 ’20 110w
“But, after all, it is Baltazar himself who is the book, and he is always a joy.”
N Y Times 25:38 Ja 25 ’20 1150w
Outlook 124:430 Mr 10 ’20 200w
“A captious reader might complain that Mr Locke has tried to do too many things at once, that a single novel simply has not sufficient space to include the big issues of feminism, profiteering, labour unrest and the thousand and one elements of contemporary social upheaval. But Mr Locke’s readers are not inclined to be captious.” F. T. Cooper
Pub W 97:173 Ja 17 ’20 550w
“The writing is pleasant and workmanlike, and the way in which the elder woman of the story is led to reknit her broken romance is exceedingly well imagined.”
Sat R 129:477 My 22 ’20 130w
“Mr Locke has given us an ingenious and amusing story, but gratitude for this gift cannot prevent even an indolent reviewer from protesting mildly against the strain he has imposed on our credulity.”
Spec 124:462 Ap 3 ’20 550w
“Baltazar is very likeable in his forceful domineering strength, and Marcelle is a charming foil to his powerful personality. The lighter element is supplied by the Chinaman.”
“Mr W. J. Locke goes on his way regardless of the limits between the probable and the improbable. John Baltazar stretches the credulity of the reader to the utmost from the moment that he enters on the scene. ”
The Times [London] Lit Sup p139 F 26 ’20 550w
LOCKEY, JOSEPH BYRNE. Pan-Americanism: its beginnings. *$5 Macmillan 327
20–7662
The author’s preface points out that Pan-Americanism has passed through three periods, the first, characterized by a tendency toward solidarity, the second, by an opposite tendency toward separation and distrust, the third marked by a revival of the earlier trend. This book is devoted to the first of these periods, extending to about 1830 and embracing the years of revolution and the formation of new states. The eleven chapters are devoted to: Meaning of PanAmericanism; Formation of new states; Failure of monarchical plots; United States and Hispanic American independence; International complications; Hispanic America and the Monroe doctrine; Early projects of continental union; The Panama congress; British influence; Attitude of the United States; Argentina, Brazil, and Chile. There is a bibliography of nineteen pages, followed by an index. The
work was completed as an “academic task” at Columbia university under the direction of Professor John Bassett Moore.
“A thorough and authoritative study.”
Booklist 17:148 Ja ’21
“With the substance of the book little fault can be found. It is timely and valuable. The arrangement and style are likely, however, to elicit some adverse criticism. The style abounds in colloquialisms, redundant words, and inexact expressions. But these slight imperfections do not seriously detract from or obscure the thought of an otherwise excellent work.” W: R. Manning
Y Evening Post p4 O 30 ’20 870w R of Rs 62:223 Ag ’20 60w Spec 125:471 O 9 ’20 1600w
“Interesting and scholarly study.”
LOCKINGTON, W. J. Soul of Ireland; with an introd. by G. K. Chesterton. *$1.75 Macmillan 941.5
20–824
“The gist of this [book is] that ‘Ireland is a proof, that the whole world may see, of the joy of life and sanity of outlook that spring from the Catholic church, the church of the tabernacle’: aliter that ‘the Irishman fearlessly stands before the whole world and unhesitatingly proclaims that his greatest pride and his greatest glory is the heritage that was given him by St Patrick our Holy Catholic faith.’” The Times [London] Lit Sup
Ath p1387 D 19 ’19 40w
Booklist 16:240 Ap ’20
“Father Lockington employs a bombastic style unfortunately characteristic of a class of books about Ireland, books against which nearly all the younger Irish writers have revolted. It is surprising to find an author of Mr Chesterton’s literary standing writing an introduction to ‘The soul of Ireland’: readers who care for literature will be wise to go no further.” N. J. O’C.
Boston Transcript p6 F 25 ’20 180w
“Long, sickly, sentimental rhapsody, in the rococo style.” Preserved Smith
Nation 110:556 Ap 24 ’20 150w
“It is written in a lofty, almost poetic, style, and a deep religious fervor pervades it throughout.”
N Y Times 25:225 My 2 ’20 500w
“Even those who stand outside the sacred circle for which he writes and who can not share the glowing devoutness of his symbolism must be moved by the enthusiastic tenderness with which this Jesuit priest idealizes the land of his ministry.” H. L. Stewart
Review 2:284 Mr 20 ’20 150w
The Times [London] Lit Sup p679 N 20 ’19 70w
LODGE, RUPERT CLENDON.
Introduction to modern logic. $2 (1c) Perine bk. co., 1413 University av., S. E., Minneapolis, Minn. 160
20–5668
An introductory text book prepared by an assistant professor of philosophy in the University of Minnesota. “By ‘modern’ logic is understood that body of logical theories and methods which is usually associated with the names of Lotze, Sigwart, Bradley, Bosanquet, Wundt, Erdmann and Dewey.... The traditional or Aristotelian logic, which has played so great a part in the past history
“In this purpose to develop comprehensively the constructive theory of ‘modern logic,’ the author has admirably succeeded. The presentation marches. Compactness, explicitness, the constant use of illustration, and clarity in development are its outstanding features.”
C. I. Lewis
+ − of thought, is entirely omitted from consideration, as are also symbolic logic and the various attempts at inventing a logical calculus. For all such omissions, as well as for what is included, the sole justification is the nature of an introductory treatise.” (Preface) The book is in three parts: Judgment; Inference; and Scientific method. Each chapter is followed by references and exercises and there is an index to authorities referred to in the text as well as a general index.
J Philos 17:498 Ag 26 ’20 1200w
LOEB, MRS SOPHIE IRENE (SIMON). Everyman’s child. il *$2 Century 362.7
20–17501
The author is the president of the New York city Board of child welfare and has personally studied the child welfare work done in various European countries and in the United States. The book describes the urgency of state laws to protect the children of the poor and what has already been done in that direction through the Widow’s pension law. Among the contents are: The cry of the children; What is being accomplished; Homes instead of institutions for the children of Uncle Sam; Importance of home life to children; How children keep out of children’s court; How the other half dies;
The unwanted child; Boarded-out children. There are illustrations and an appendix.
Booklist 17:94 D ’20
“Miss Loeb’s book is written with care and out of her manifold experience; but it is written also in enthusiasm. The book represents the most progressive thoughts on these problems and is worthy of a careful reading.”
Boston Transcript p6 D 4 ’20 290w
Wis Lib Bul 16:233 D ’20 40w
LOFTING, HUGH.
Story of Dr Dolittle; being the history of his peculiar life at home and astonishing adventures in foreign parts. il *$2.25 Stokes
20–18925
A very jolly nonsense story. Dr Dolittle loves animals and fills his house with queer pets, to the dismay of many of his patients. His sister warns him that if he keeps on none of the best people will have him for a doctor. But he loves animals better than he does the best people and the result is that his practice all falls off. So he gives up being a people’s doctor to become an animal doctor. He learns their language, Polynesia his parrot acting as his teacher. When the opportunity comes to go to Africa to cure the monkeys of a strange
disease he is ready for it, and there he has most curious and interesting adventures. The illustrations are by the author.
“The most delightful nonsense story of the year. ” A. C. Moore
Bookm 52:260 N ’20 360w
“An invigorating, fascinating tale, its quaintness enhanced by the droll illustrations.”
Dial 69:548 N ’20 60w
“It is a pleasant surprise to open a volume whose illustrations appeal because of their inherent nonsense, and to find the author, who is as well the illustrator, maintaining a delightful sense of proportion in his imagination.”
Lit D p89 D 4 ’20 200w
“This is the best ‘animal’ story we remember to have come across in a long time, imbued with a real love and understanding of animals and with a humor which is fresh and quaint.”
N Y Evening Post p19 D 4 ’20 240w
“Is as fascinating as it is queer.” Hildegarde Hawthorne
N Y Times p9 D 12 ’20 250w
LOMAX, JOHN AVERY, comp. Songs of the cattle trail and cow camp; with a foreword by William Lyon Phelps. *$1.75 Macmillan 811.08
19–18742
“Those who enjoyed the rough but hearty lyrics in ‘Cowboy songs, and other frontier ballads’ will wish to read these later collections by the same author, now working under a Harvard fellowship. The later volume has no music scores, and many of the poems can definitely be assigned to authors, among them, Charles Badger Clark, jr. and Herbert H. Knibbs.” Booklist
Booklist 16:195 Mr ’20
“Some of these pieces are clearly as spurious as are the seventeenth century lyrics of Strephon and Colin. Others are more true to life.”
Nation 110:306 Mr 6 ’20 280w
“Whatever may be the literary poverty of the verse in Mr Lomax’s book, the poems are true to type. Many of the ‘Songs of the cattle trail’ are worth little, perhaps, in themselves. Collected, they form both a picture and a plea: a picture of a vitally individual and highlycolored life that is rapidly fading into the monotone of a mechanical civilization; a plea for a deeper, finer art-interpretation of that life.”
Natalie Curtis
Nation 111:591 N 24 ’20 2200w
“It is a pleasure to read verse that is unpretentiously natural, in which something happens, and in which nature is allowed to seem as robust and hearty as she really is. Professor Lomax has done well by his country in presenting these rough songs of adventure in the West.” Marguerite Wilkinson
N Y Times 25:140 Mr 28 ’20 550w
“The volume is essentially a book of the soil, truly interpretative of an element of our national life which has practically faded away. ”
Springf’d Republican p10 Mr 26 ’20 500w
“This new collection of songs written by and for cowboys is more interpretive of the American spirit than the third-rate material from Greenwich village with which most of our literary periodicals fill their pages. Somewhat surprising, perhaps, to those whose idea of its life is taken from films and fiction, is the chastity of thought and diction in this folk-literature of the Far West. Its realism, and often its humor, is altogether delightful.” B. L. Survey
